1. Field of the Invention
The present invention relates generally to an RF vector modulator for beamforming. More particularly, the present invention relates to the beamforming RF vector modulator which can simply implement the beamforming with low power in the next-generation Gbps-level WPAN.
2. Description of the Related Art
To provide directional wireless communication (i.e., increase the signal strength by focusing the energy of an RF signal transmitted in a specific direction), transceivers can adopt a beamforming technique. In general, the beamforming technique is a baseband processing technique for generating the focused antenna beam by shifting the signal in the time or in the phase so as to offer the gain of the signal in an intended direction and to attenuate the signal in other directions.
For doing so, a system can be constituted by including the array of antennas, transmitters, and receiver in a reception part and a transmission part respectively. The beamforming technique maximizes Signal Noise Ratio (SNR) by forming the beam in the intended direction as shown in FIG. 1, and regulates the beam radiated from the antenna by applying different phase magnitudes to the transmitters and the receivers.
In this regard, a first conventional beamforming technique is disclosed in Korean Patent Registration No. 10-0809313, which relates to a method for enhancing wireless communication performance with a plurality of antennas and a plurality of RF receivers by selecting the receiver of the strongest power fed into to the receiver. The Korean Patent Registration No. 10-0809313 requires the plurality of the receivers and acquires no transmission and reception gain through the beamforming.
Second, Korean Patent Registration 10-0465314 realizes the antenna beamforming using a digital beamforming scheme such as antenna isolated over a certain distance, multichannel converter, correlation vector estimator, and beamformer. Korean Patent Registration 10-0465314 requires analog circuits as many as the antennas and exhibits too low power consumption and signal processing rate to process the high speed data in the next-generation WPAN. Hence, its application is limited in the high-speed and low-power data communication system.
Third, Korean Patent Registration 10-0474849 applies an algorithm for enhancing the communication performance by adopting the beamforming technique. For the beamforming, the disclosed method forms the beam in the intended direction as shown in FIG. 1 by regulating the phase and the amplitude into each antenna. The beamforming method of FIG. 1 also requires a plurality of transceivers and does not describe a detailed design for generating the phase and the amplitude.
The second and third techniques form the beam in the intended direction by digitally controlling the beamforming and thus improve the communication performance as a greater number of transceivers are used. However, there occur various problems such as the number of the transceivers and the consumption of resources for the signal processing.
Wireless Personal Area Network (WPAN) is a wireless network enabling devices in a short range to communicate data with low power. The WPAN performs the data communication using Time Division Multiple Access (TDMA) scheme. Accordingly, the devices for the data communications exclusively occupy the channel during a time (Channel Time Allocation Period (CTAP)) allocated from a device called a Piconet Coordinator (PNC) and communicate data.
The 60 GHz communication, which is the next-generation WPAN, cannot apply the conventional beamforming techniques as discussed above as the Gbps-level based wireless data communication system. In addition, an RF beamformer used for military use needs to be replaced with a commercial technique in terms of the size, the power consumption, and the cost.